Radioimmunoassay for human growth hormone using monoclonal antibodies

Radioimmunoassay (RIA's) for human growth hormone (hGH) employing monoclonal antibodies (Mab) were compared with a conventional clinical RIA using polyclonal antibodies (PAb). Several MAb displayed sensitivities (defined as the concentration of hormone required for 50% inhibition of binding of 125I-hGH) for hGH in the RIA which were equivalent to those of PAb. Those MAb with the greatest sensitivity for hGH displayed an equal affinity for human placental lactogen (hPL), whereas those with lower sensitivity for hGH, cross-reacted minimally with hPL. The concentrations of hGH in human serum samples were determined with MAb and the values showed a high degree of correlation with those obtained by PAb. It is therefore concluded that MAb are useful for the development of clinical RIA's for polypeptide hormones.